1. Field of the Invention
This invention generally relates to an object recognizing apparatus and more particularly to a contour detecting apparatus for detecting the position of a specific object for use in automobile equipment and in a factory automated by using a robot and so on.
2. Description of the Related Art
A typical apparatus and a method for detecting a position or contour of an object as disclosed in the Japanese Patent Application Provisional Publication No. 60-215284. The typical method comprises steps of first calculating run-length of each sequence of pixels or picture elements having same intensity on a path of the object such as a semicircle and then determining the position of the object by detecting the position of a pixel at which the intensity thereof changes from that of the adjacent pixel. This conventional technique is applied to, for example, inspection of a speedometer of an automobile as follows. First, run-length of each sequence of pixels having same intensity on a periphery of an inscribed square of a major arc CDAB which is a path of an end portion of an indicator of a speedometer (see FIGS. 10(a) and 10(b)). Then, the current position of the indicator on the square is detected on the basis of change in the intensity of pixels. Further, the corresponding position .alpha. of the end portion of the indicator on the arc is calculated from the calculated run-lengths.
Such a typical apparatus, however, has drawbacks that the position of an object to be recognized cannot be detected if the image or picture of the object is blurred by a stain and lustre on the surface of the object further, when the position detection of an object having an concavity in the contour thereof is attempted, the position detection of such an object cannot be performed due to the difference between the position data of the point of the inflection and the predetermined correct position of the point of the inflection, which difference is caused by a concavity of the object.
The present invention is accomplished to eliminate such drawbacks of the typical apparatus above described.